Ms Hardy said a range of factors played a part in how people acted when drinking alcohol.

"Reports and research indicate that it isn't necessarily alcohol that creates the anger," she said.

"Age, gender, size, weight, personality traits, predisposition to aggression and many other things also play a part.

"Someone who gets angry when drinking is likely to be carrying anger generally and have less emotional control, even if it is not necessarily obvious to others, when they are sober.

"And they may also be in the category of those that go out seeking violence to obtain status and reputation, with or without alcohol."

Ms Hardy said DNA could not be blamed for booze-fuelled violence.

"I would say that it has less to do with DNA and more to do with what the person has observed and experienced around them growing up," she said.

"What was acceptable in the family and the social culture around them, particularly in early childhood when everything is absorbed unconsciously, paves the way for future programming and creates a belief that this is the way we do things around here."

What happens when we drink

- When alcohol is consumed it passes quickly through the blood-brain barrier affecting the neurons in the brain.

- This causes it to react differently, reducing inhibitions and limiting the ability to apply its normal braking system to stop an emotional response accelerating.

- The pre-frontal cortex, which is responsible for decision-making and rational thought and has a role in preventing aggressive behaviour, is also involved.

- Alcohol causes a decrease in activity in the pre-frontal cortex which results in the person acting without thinking rationally